[icalendar] Fixed issues with moved events and wrong displayed events (#9678)

[icalendar] Fixed issues with moved events and wrong displayed events (#9678)

* [icalendar] Fixed issues with moved events and wrong displayed events
* [icalendar] Changed test to use local time in test-calendar of #9647

Fixes #9647.

Handling for RFC 5545's RECURRENCE-ID field inside of
events and rounded begin (and based on it end) down in subsecond
precision.

The calendar does not define a timezone. On a machine that uses a
different timezone than Europe/Berlin the test failed. As the behavior
itself is specified, the test was changed to use local time for its
dates.

Signed-off-by: Michael Wodniok <michi@noorganization.org>